1. Field of the Invention
The present invention relates to a process for production of crystalline galloalumino silicate and a process for production of aromatic hydrocarbons. More particularly, it relates to a process for efficiently producing crystalline galloalumino silicate having excellent catalyst performance, and a process for efficiently producing aromatic hydrocarbons by the use of the above crystalline galloalumino silicate as a catalyst.
2.Description of Related Art
In production of aromatic hydrocarbons from various hydrocarbon materials, various zeolites have been used as the catalyst. For example, a method in which crystalline galloalumino silicate modified with steam is used as the catalyst in producing aromatic hydrocarbons from a hydrocarbon material having 2 to 12 carbon atoms(PCT Japanese Application Laid-Open No. 501357/1985), a method in which cryalline gallium silicate wherein SiO.sub.2 /Ga.sub.2 O.sub.3 =25 to 100 (molar ratio), Y.sub.2 O.sub.3 /Ga.sub.2 O.sub.3 &lt;1 (molar ratio)(wherein Y is Al, Fe, Co or Cr) is used as the catalyst in producing aromatic hydrocarbons from an aliphatic hydrocarbon mixture containing paraffins having 2 to 4 carbon atoms in a proportion of more than 50% (Japanese Patent Application Laid-Open No. 98020/1984), and a method in which crystalline gallium silicate wherein SiO.sub.2 /Ga.sub.2 O.sub.3 =25 to 250 (molar ratio), Y.sub.2 O.sub.3 /Ga.sub.2 O.sub.3 &lt;1 (molar ratio)(wherein Y is Al, Fe, Co or Cr) and which has been subjected once or several times to a two stage treatment comprising the first stage wherein 0.1 to 5% by weight of cokes is deposited and the second stage wherein the gallium silicate is contacted with an oxygen containing gas at a temperature of 350.degree. to 700.degree. C., or alternatively has been calcined for 2 to 8 hours at a temperature of 600.degree. to 1,000.degree. C. before the above two stage treatment is used as the catalyst in producing aromatic hydrocarbons from an aliphatic hydrocarbon mixture containing paraffins having 2 to 4 carbon atoms in a proportion of more than 50% (Japanese Patent Application Laid-Open No. 98022/1984) are known.
However, the method disclosed in PCT Japanese Laid-Open No. 501357/1985 has disadvantages in that the yield of aromatic hydrocarbons is low and the catalytic life is short. The method disclosed in Japanese Patent Application Laid-Open No. 98020/1984 also has a disadvantage in that the catalytic life is short. The method disclosed in Japanese Patent Application Laid-Open No. 98022/1984 has disadvantages in that a plurality of steps are needed in the preparation of the catalyst and thus the process of preparation of the catalyst becomes complicated and, furthermore, the yield of aromatic hydrocarbons is low and the catalytic life is still insufficiently short.